The present invention relates to hindered chlorinated primary amines, which are useful as preservatives for latex formulations.
There is an ongoing need to improve latex preservation; in spite of the availability of well-developed biocide packages in latex products, microbial spoilage still occurs. Although the rate of catastrophic spoilage is low, each event diminishes consumer relationships and confidence.
In addition to preserving a microbe-free environment for latexes in final formulated products, there is a need to improve the efficiency of cleaning the interior surfaces of pipes, vessels, and process equipment without disassembly. This so-called “clean-in-place” technology often includes a sanitize cycle to reduce bacterial contamination using a biocide such as a hypochlorite or an isothiazolone, which kill microbes quickly and completely. Isothiazolones such as KATHON™ Preservatives (A Trademark of The Dow Chemical Company or its Affiliates) are especially attractive because they show a broad spectrum of biocidal activity as well as efficacy at low ppm levels.
On the other hand, isothiazolones tend to have relatively short shelf-life stability (4-6 months), requiring more frequent addition of isothiazolones or bleach to preserve the integrity of the latex. However, bleach and other chlorine-based oxidants are known to adversely impact the properties of the latex and, over time, the integrity of the vessel containing the latex. Furthermore, the activity of bleach and other chlorine based oxidants is limited due to the quick release of chlorine.
Chlorinated hindered amines have recently been proposed as anti-microbial agents for latex paint formulations. For example, Cao et al. discloses the synthesis of N-chloro-2,2,6,6-tetramethyl-4-piperidinyl methacrylate (Cl-TMPM) and its subsequent conversion to the latex polymer polyCl-TMPM, which is described as being useful as a biocide for latex paints. (Cao, Z; Sun, Y; ACS Appl. Mater. Interfaces, 2009, 1(2), 494-504). Paints formulated with polyCl-TMPM were found to provide potent long-lasting (>1 year) antimicrobial activities against a wide range of bacteria and to prevent biofilm formation and development. Nevertheless, paints required 1 to 20 weight percent of the latex biocide to achieve quick kill. Consequently, the high levels of additive would be expected to have an adverse impact on the properties and cost of the paint.
Accordingly, it would be desirable to find alternative biocides or biocide packages that have quick kill capability at low concentrations and long shelf stability without adversely affecting the integrity of materials of construction of vessels. It would further be desirable to find inexpensive packages that do not require the development of new biocidal actives that would be subject to costly and time-consuming approval by regulatory agencies.